Pyridoxamine for the treatment of diabetic kidney disease

ABSTRACT

The present invention provides pharmaceutical compositions comprising dosage units of pyridoxamine, or a pharmaceutically acceptable salt thereof; and a pharmaceutically acceptable carrier, and methods for their use in limiting the progression of renal disease and/or diabetic complications in human diabetic patient.

CROSS REFERENCE

The present application claims priority to U.S. Provisional PatentApplications Ser. Nos. 60/480,032 filed Jun. 20, 2003 and 60/562,062filed Apr. 14, 2004, each of which is hereby incorporated by referencein its entirety.

BACKGROUND OF THE INVENTION

Nephropathy develops in 30 to 40 percent of patients with Type 1diabetes, and in an estimated 10 to 15 percent of patients with Type 2diabetes. An early sign of the disease includes the loss of protein(particularly albumin) into the urine (“proteinuria” or “albuminuria”).As renal damage progresses, patients lose the ability to effectivelyfilter the blood in the glomerulus and can progress to the need fordialysis or transplantation. Diabetic nephropathy, and in particulardialysis and transplantation, is costly both in terms of medicaltreatment and in lost productivity. Treatment that prevents or limitsthe development or progression of diabetic nephropathy will meet asignificant medical need and provide significant cost savings to thehealth care system.

Increased levels of advanced glycation end-products (AGEs) in theglomerular basement membrane are regarded as a major contributing factorin the development of diabetic nephropathy. Circulating levels of AGEsare elevated in diabetic patients and increase dramatically when renalfunction begins to decline. A large body of evidence has demonstratedthat pyridoxamine, a potent AGE inhibitor, can dramatically inhibit theprogression of kidney disease in treated animals compared to untreatedcontrol animals.

SUMMARY OF THE INVENTION

In one aspect, the present invention provides pharmaceuticalcompositions comprising (a) a dosage unit of 25 mg to 1000 mg ofpyridoxamine, or a pharmaceutically acceptable salt thereof; and (b) apharmaceutically acceptable carrier.

In another aspect, the present invention provides pharmaceuticalcompositions comprising: (a) pyridoxamine, or a pharmaceuticallyacceptable salt thereof; and (b) one or more compounds selected from thegroup consisting of angiotensin converting enzyme inhibitors,angiotensin receptor blockers, beta-blockers, aldose reductaseinhibitors, calcium blockers, diuretics, glycosaminoglycans, incretinmimetics, insulin, insulin sensitizers, statins, fibrates, glucoseuptake inhibitors, sulfonylureas, superoxide dismutase (SOD) and SODmimetics, thiamine pyrophosphate and its prodrugs, transketolaseinhibitors, other AGE inhibitors that can mechanistically complementpost-Amadori-inhibitors, and protein kinase C inhibitors. In a preferredembodiment, the one or more compounds are selected from the groupconsisting of angiotensin converting enzyme inhibitors and angiotensinreceptor blockers, or pharmaceutically acceptable salts thereof.

In a further aspect, the present invention provides methods for limitingthe progression of renal disease and/or diabetic complications in ahuman diabetic patient, comprising administering to the human diabeticpatient an amount of pyridoxamine, or a pharmaceutically acceptable saltthereof, effective to limit the progression of renal disease and/ordiabetic complications in the diabetic human patient.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a table summarizing the clinical trial data (PYR-206).

FIG. 2(a)-(b) summarize the baseline patient demographics from theclinical trial (PYR-206).

FIG. 3 summarizes the adverse events from the clinical trial (PYR-206).

FIG. 4 summarizes adverse events by body system (PYR-206).

FIG. 5 summarizes neurological adverse events in the sensory system(PYR-206).

FIG. 6 summarizes tests that exceeded a pre-designated cut-off(PYR-206).

FIG. 7(a)-(b) summarizes the baseline demographics from the secondclinical trial (PYR-205/207)

FIG. 8 summarizes the efficacy findings from the second clinical trial(PYR-205/207)

FIG. 9 provides a comparison of the pyridoxamine clinical trial resultsto the results of clinical trial using other therapeutics to treatdiabetic nephropathy.

DETAILED DESCRIPTION OF THE INVENTION

The present invention provides pharmaceutical compositions ofpyridoxamine, and methods for using such compositions in human diabeticpatients.

In a first aspect, the present invention provides pharmaceuticalcompositions, comprising (a) 25 to 1000 milligrams of pyridoxamine, or apharmaceutically acceptable salt thereof, and (b) a pharmaceuticallyacceptable carrier.

Dosage unit forms of the pharmaceutical compositions of the presentinvention comprise between 25 mg and 1000 mg of pyridoxamine, or apharmaceutically acceptable salt thereof. Such dosage unit forms cancomprise, for example, 25, 50, 75, 100, 125, 150, 175, 200, 250, 300,350, 400, 450, 500, 550, 600, 650, 700, 750, 800, 850, 900, 950, or 1000mg of pyridoxamine, or a pharmaceutically acceptable salt thereof, orany range of such dosage unit forms. In a preferred embodiment, thedosage unit forms of the pharmaceutical compositions comprise between 50mg and 500 mg of pyridoxamine, or a pharmaceutically acceptable saltthereof. Such dosage unit forms can comprise, for example, 50, 75, 100,125, 150, 175, 200, 250, 300, 350, 400, 450, or 500 mg of pyridoxamine,or a pharmaceutically acceptable salt thereof. The dosage unit form canbe selected to accommodate the desired frequency of administration usedto achieve a specified daily dosage of pyridoxamine, or apharmaceutically acceptable salt thereof, to a patient in need thereof.Preferably the unit dosage form is prepared for once daily or twicedaily administration to achieve a daily dosage of between 50 and 2000mg, more preferably between 100 and 1000 milligrams.

Therapeutic approaches to treating diabetic nephropathy currently followtwo strategies: the use of antihypertensive medications to treathemodynamic factors, and the use of drugs to control blood glucose andthe consequences of hyperglycemia (metabolic factors). It has been foundthat antihypertensive agents can retard the progression of diabeticnephropathy by lowering renal intra-glomerular pressure. Blockade of therenin-angiotensin system is currently the most common approach toachieve this. The angiotensin converting enzyme (ACE) inhibitor,captopril, was first approved for this indication in type 1 diabetes,but it and other ACE inhibitors are routinely also prescribed fornephropathy in type 2 diabetes. Very recently, blockade of theangiotensin 2 (type 1) receptor (ARB) has been demonstrated to havevalue, with losartan and irbesartan getting FDA approval for thetreatment of nephropathy due to type 2 diabetes mellitus. Othermodalities include use of diuretics (thiazides), beta blockers andcalcium blockers. However, it is recognized that these treatmentsgenerally retard but do not prevent the progression of diabetic renaldisease beyond their anti-hypertensive actions.

The second approach to treatment is to treat metabolic factorsassociated with elevated glucose (hyperglycemia). Strict glucose controlis attempted with insulin, insulin sensitizers, insulin secretalogues,metformin, inhibitors of glucose absorption from the gastrointestinaltract and similar medications. However, perfect glucose control cannotbe achieved, and it is recognized that even diabetics maintainingexcellent glucose control will still experience damaging fluctuations oftheir glucose in the blood. Other medications are being developed tohalt damage from hyperglycemia, such as protein kinase C inhibitors,superoxide dismutase (SOD) and SOD mimetics, thiamine pyrophosphate andits prodrugs, transketolase inhibitors, other AGE inhibitors that canmechanistically complement post-Amadori-inhibitors, glucosaminoglycans,and aldose reductase inhibitors.

A newer approach that can be combined with all the metabolic andhemodynamic therapies is to use agents that halt the direct damage thatglucose causes to proteins. Pyridoxamine represents the most promisingof this class of compounds designed as inhibitors of the formation oftoxic advanced glycation end products that contribute to diabeticcomplications. Pyridoxamine can be used with these other medications tooptimize treatments of general patient populations or with specificpatient subpopulations that resist treatment by these other modalities.For example, it is recognized that not all patients tolerate ACEinhibitors or respond to them, but it is possible that the combinationwith pyridoxamine may prove to be superior to these therapies. Suchco-administration of current therapeutics with pyridoxamine may alsopermit administration of lower dosages of these other therapeutics, thusminimizing potential side effects.

Thus, in a further aspect, the present invention provides pharmaceuticalcompositions comprising (a) pyridoxamine, or a pharmaceuticallyacceptable salt thereof; and (b) one or more compounds that can providehemodynamic and/or metabolic improvement in a human patient, orpharmaceutically acceptable salts thereof. In a preferred embodiment,such compounds are selected from the group consisting of angiotensinconverting enzyme inhibitors (ACE-I), angiotensin receptor blockers(ARB), beta-blockers, aldose reductase inhibitors, calcium blockers,diuretics, glycosaminoglycans, incretin mimetics, insulin, insulinsensitizers, statins, fibrates, glucose uptake inhibitors,sulfonylureas, superoxide dismutase (SOD) and SOD mimetics, thiaminepyrophosphate and its prodrugs, transketolase inhibitors, other AGEinhibitors that can mechanistically complement post-Amadori-inhibitors,and protein kinase C inhibitors. The combination of such compounds withpyridoxamine is demonstrated herein to be effective for limiting theprogression of renal disease and diabetic complications in humandiabetic patients.

In a preferred embodiment of this aspect of the invention, the one ormore compounds are selected from the group consisting of angiotensinconverting enzyme inhibitors and angiotensin receptor blockers, orpharmaceutically acceptable salts thereof, in a pharmaceuticallyacceptable carrier. Non-limiting examples of angiotensin convertingenzyme inhibitors for use in the present invention include benazepril,benazeprilat, captopril, delapril, fentiapril, fosinopril, libenzapril,moexipril, pentopril, perindopril, pivopril, quinapril, quinaprilat,ramipril, spirapril, spiraprilat, zofenopril, ceronapril, enalapril,indolapril, lisinopril, alacepril, and cilazapril, or pharmaceuticallyacceptable salts thereof.

Non-limiting examples of angiotensin receptor blockers for use in thepresent invention include losartan, candesartan, irbesartan, olmesartan,valsartan, telmisartan, eprosartan, and tasosartan.

Pharmaceutically acceptable salts in accordance with the presentinvention, are salts with physiologically acceptable bases and/or acidswell known to those skilled in the art of pharmaceutical technique.Suitable salts with physiologically acceptable bases include, forexample, alkali metal and alkaline earth metal salts, such as sodium,potassium, calcium and magnesium salts, and ammonium salts and saltswith suitable organic bases, such as methylamine, dimethylamine,trimethylamine, piperidine, morpholine and triethanolamine. Suitablesalts with physiologically acceptable acids include, for example, saltswith inorganic acids such as hydrohalides (especially hydrochlorides orhydrobromides), sulphates and phosphates, and salts with organic acids.

The pharmaceutical compositions of this aspect of the invention includeadmixtures of the pyridoxamine, or pharmaceutically acceptable saltthereof, and the one or more other compounds, as well as separate unitdosages of each that are manufactured for combinatorial use. Suchseparate unit dosages may be administered concurrently or sequentiallyas determined by the clinician.

In all aspects of the pharmaceutical compositions of the presentinvention, the compounds are combined with one or more pharmaceuticallyacceptable carriers appropriate for the indicated route ofadministration. The compounds may be admixed with lactose, sucrose,starch powder, cellulose esters of alkanoic acids, stearic acid, talc,magnesium stearate, magnesium oxide, sodium and calcium salts ofphosphoric and sulphuric acids, acacia, gelatin, sodium alginate,polyvinylpyrrolidine, and/or polyvinyl alcohol, and tableted orencapsulated for conventional administration. Alternatively, thecompounds of this invention may be dissolved in saline, water,polyethylene glycol, propylene glycol, carboxymethyl cellulose colloidalsolutions, ethanol, corn oil, peanut oil, cottonseed oil, sesame oil,tragacanth gum, and/or various buffers. Other adjuvants and modes ofadministration are well known in the pharmaceutical art. The carrier ordiluent may include time delay material, such as glyceryl monostearateor glyceryl distearate alone or with a wax, or other materials wellknown in the art.

In a preferred embodiment of each of the above aspects of the invention,the pharmaceutical compositions of the invention are prepared for oraladministration. As such, the pharmaceutical composition can be in theform of, for example, a tablet, a hard or soft capsule, a lozenge, acachet, a dispensable powder, granules, a suspension, an elixir, aliquid, or any other form reasonably adapted for oral administration.The pharmaceutical compositions can further comprise, for example,buffering agents. Tablets, pills and the like additionally can beprepared with enteric coatings. Unit dosage tablets or capsules arepreferred.

Pharmaceutical compositions suitable for buccal administration include,for example, lozenges comprising pyridoxamine, or a pharmaceuticallyacceptable salt thereof and a flavored base, such as sucrose, acaciatragacanth, gelatin, and/or glycerin.

Liquid dosage forms for oral administration can comprisepharmaceutically acceptable emulsions, solutions, suspensions, syrups,and elixirs containing inert diluents commonly used in the art, such aswater. Such compositions can also comprise, for example, wetting agents,emulsifying and suspending agents, and sweetening, flavoring, andperfuming agents.

These pharmaceutical compositions can be prepared by any suitable methodthat includes the step of bringing into association pyridoxamine, or apharmaceutically acceptable salt thereof (and optionally the othercompounds) and the pharmaceutically acceptable carrier. In general, thecompositions are prepared by uniformly and intimately admixing thepyridoxamine, or a pharmaceutically acceptable salt thereof, with aliquid or finely divided solid carrier, or both, and then, if necessary,shaping the product. For example, preparation of tablets can comprisecompressing or molding a powder or granule of the compound. Compressedtablets can be prepared by compressing, in a suitable machine, thecompound in a free-flowing form, such as a powder or granules optionallymixed with a binding agent, lubricant, inert diluent and/or surfaceactive/dispersing agent(s). Molded tablets can be made by molding, in asuitable machine, the powdered compound moistened with an inert liquiddiluent.

In another aspect, the present invention provides methods for limitingthe progression of renal disease and/or diabetic complications in adiabetic human patient by administering to the patient an amount ofpyridoxamine, or a pharmaceutically acceptable salt thereof, effectiveto limit the progression of renal disease or diabetic complications inthe diabetic patient. In a preferred embodiment, the methods compriseadministering the pharmaceutical compositions of the invention to thepatient. Thus, a preferred embodiment of the method comprisesadministering between 50 and 2000 milligrams of pyridoxamine, or apharmaceutically acceptable salt thereof, to the patient, morepreferably between 100 and 1000 milligrams of pyridoxamine, or apharmaceutically acceptable salt thereof.

As used herein, “diabetic patient” encompasses both Type 1 and Type 2diabetic patients and “diabetes” encompasses both Type 1 and Type 2diabetes.

As used herein, “limiting the progression of renal disease” means toreduce or prevent decreases in renal function in those patientsreceiving treatment relative to diabetic patients not receiving thetreatment. Such treatment thus reduces the need for kidney dialysis ortransplantation in diabetic patients.

The progression of renal disease can be measured in various ways,including the following:

-   -   (a) Proteinuria (ie: increased loss of protein into the urine;        often assessed by measurement of albumin levels (ie:        “albuminuria”));    -   (b) Impaired glomerular filtration (ie: kidney function to clear        substances from blood; can be measured, for example, by        creatinine (ic: “impaired creatinine clearance”), inulin, or        urea clearance);    -   (c) Increased levels of serum creatinine; and    -   (d) Increased levels of urinary transforming growth factor beta        (TGF-β).

Thus, the methods of the invention can be used, for example, to limitthe increase in one or more of proteinuria, albuminuria, serumcreatinine levels, and urinary TGF-β levels, and/or to limit theimpairment of glomerular filtration and/or creatinine clearance in adiabetic patient being treated with pyridoxamine, a pharmaceuticallyacceptable salt thereof, or one of the pharmaceutical compositions ofthe invention relative to a diabetic patient not receiving suchtreatment. As will be understood by those of skill in the art, afavorable effect of the methods of the invention on any one or more ofthese measures of renal disease constitutes limiting the progression ofrenal disease.

In a preferred embodiment, measuring urinary TGF-β comprisesconcentrating urinary samples according to standard protocols (forexample, use of an Ultra-4 concentrator), and measuring the urinaryconcentration at a desired time point after initiation of treatment.

As used herein, “limiting the progression” of diabetic complicationsmeans slowing or stopping the progression of diabetic complications inthose patients receiving treatment relative to diabetic patients notreceiving the treatment. Thus, the methods of the invention can be used,for example, to slow or stop the progression of nephropathy, neuropathy,retinopathy, and/or symptoms due to impaired microvascular (e.g.erectile dysfunction, angina, claudication) or macrovasular (MI, CVA,amputation, etc.) complications of diabetes in diabetic patientsreceiving treatment relative to diabetic patients not receiving suchtreatment.

As used herein, “nephropathy” refers to kidney disease, inflammation, ordamage; “neuropathy” refers to a disease, inflammation, or damage to thenervous system; symptoms include numbness, tingling, pain, or muscleweakness, depending on the nerves affected. In a further preferredembodiment, the methods serve to limit one or more symptoms ofneuropathy selected from the group consisting of areflexia (reflexesabsent), hyporeflexia (weakened reflexes), paresthesia (abnormalsensation, such as burning, pricking, or numbness), peripheralneuropathy (disease, inflammation, or damage to the peripheral nervoussystem), aggravated peripheral neuropathy, and sensory loss (partial orcomplete loss of sensory function). As used herein, “retinopathy” refersto a disease, inflammation, or damage to the retina.

In a preferred embodiment of this aspect of the invention, the humandiabetic patient has type II diabetes.

In further preferred embodiment of the methods of the inventiondescribed above, the human diabetic patient being treated has a baselineserum creatinine concentration of greater than or equal to 1.3 mg/dL.

In a further embodiment of the methods of the invention, the methodsfurther comprise administering the pyridoxamine, or a pharmaceuticallyacceptable salt thereof, in combination with a further therapeutic tolimit the progression of renal disease in a human diabetic patient. Suchtherapeutics include, but are not limited to, angiotensin convertingenzyme inhibitors (ACE-I), angiotensin receptor blockers (ARB),beta-blockers, aldose reductase inhibitors, calcium blockers, diuretics,glycosaminoglycans, incretin mimetics, insulin, insulin sensitizers,statins, fibrates, glucose uptake inhibitors, sulfonylureas, superoxidedismutase (SOD) and SOD mimetics, thiamine pyrophosphate and itsprodrugs, transketolase inhibitors, other AGE inhibitors that canmechanistically complement post-Amadori-inhibitors, and protein kinase Cinhibitors. The further therapeutic can be administered together as asingle formulation with or separately from the pyridoxamine, or apharmaceutically acceptable salt thereof. In a preferred embodiment, theone or more further therapeutics comprise ACE-I and/or ARBs. In afurther preferred embodiment, the human diabetic patient is one that hasfailed to adequately respond to treatment with ACE-I and/or ARBs. Asused herein, “failed to respond adequately” means that one or moremeasures of the progression of renal disease (proteinuria, albuminuria,serum creatinine levels, impaired glomerular filtration, impairedcreatinine clearance) continue to increase despite treatment with theACE-I and/or ARBs.

In a further preferred embodiment of the various methods of theinvention, the human diabetic patient has elevated blood lipid levels,including hyperlipidemia, hypertriglyceridemia, and/orhypercholesterolemia. Such patients tend to have accelerated progressionof renal disease relative to other diabetic patients, and the datapresented herein demonstrate that treatment of these patients withpyridoxamine is more effective than treatment with the current standardof care for diabetic kidney disease.

The data presented herein also demonstrate that patients with poorglycemic control receive additional benefit from the methods of theinvention. Thus, in a further embodiment of the various methodsdescribed above, the human diabetic patient is one with poor glycemiccontrol. As used herein, “poor glycemic control” means that the patienthas an abnormal glycated hemoglobin level. The most widely acceptedmeasure of glycemic control is the whole blood level of hemoglobin A1C(HbA1C) (a glycosylated hemoglobin), with ≦6.5% HbA1C considered normal.In a preferred embodiment, the patient has a whole blood HbA1C level ofgreater than 6.5%; in further preferred embodiments, the patient has awhole blood HbA1C level of greater than 6.75%, 7%, 7.25%, or 7.275%.

While not being bound by any specific mechanism of action, it isbelieved that the beneficial effects of the methods of the invention maybe due to the inhibitory effect of pyridoxamine on the formation ofadvanced glycation end products (AGEs).

The experiments detailed below provide a striking demonstration of theefficacy of pyridoxamine dihydrochloride on limiting renal diseaseprogression in human diabetic patients compared to patients treated witha placebo. It should be noted that the placebo included the currentstandard of care for human diabetic patients: Antihypertensive careincluding the use of ACE-I or ARB treatment and treatment ofhyperglycemia and hyperlipidemia, while pyridoxamine dihydrochloride wasco-administered with ACE-I and/or ARB. Therefore, the beneficial effectof pyridoxamine dihydrochloride is in addition to any benefit thepatient would receive via administration of the current standard ofcare.

EXAMPLE

A randomized, double-blind, placebo-controlled, multicenter trial whichexamined the safety profile of pyridoxamine dihydrochloride (PYR) inpatients with type 1 and type 2 diabetes mellitus (“DM”) and overtnephropathy was conducted (“206 study”). 128 patients (48 type 1, 80type 2) at 32 sites were randomized to receive either PYR 50 mg twice aday (b.i.d) or placebo for six months. 58 patients in each groupcompleted the study. Groups were well matched at baseline for age, race,gender, blood pressure, hemoglobin A1C (HbA1C), and angiotensinconverting enzyme inhibitor (ACEI)/angiotensin receptor blocker (ARB)use.

Baseline characteristics of the patients included serum creatinine=1.27mg/dL and urinary albumin excretion=868 mg/12 h in treatment, versus1.33 mg/dL and 1055 mg/12 h in placebo groups (differences notsignificant, NS).

No significant differences in treatment-related adverse events (26% PYR,33% placebo), study discontinuation due to AE's (6% PYR, 10% placebo),serious adverse events (11% PYR, 8% placebo), or scored neurotoxicitytesting occurred during the study.

The mean rate of rise in serum creatinine was 0.223 mg/dL/yr in placeboand 0.178 mg/dL/yr in treatment groups (p=0.0065 by ANOVA).

In patients with baseline serum creatinine ≦1.3 mg/dL (baseline medianvalue), the rate was 0.45 mg/dL/yr in placebo and 0.17 mg/dL/yr in PYRgroups (p<0.0001, ANOVA).

In addition, type 2 diabetic patients with a baseline serum creatinineof ≦1.3 mg/dL, the mean rate of rise in serum creatinine was 0.519 and0.136 (p<0.0001, ANOVA) in placebo and PYR groups, respectively. In athird population of type 2 diabetic patients taking either an ACE-I orARB with a baseline serum creatinine ≧1.3 mg/dL, the rate of rise inserum creatinine was 0.138 mg/dL/yr in the PYR group and 0.407 mg/dL/yrin the placebo group (p<0.0057, ANOVA) (See Table 8). PYR substantiallyreduced the rate of increase in serum creatinine by approximately60-70%. A treatment effect of PYR to reduce the rate of urinary albuminexcretion was observed and was statistically significant using an ANOVAanalysis. However, when another method of analysis using repeatedmeasure procedures, as the ones used for the PYR-205/207 study (seebelow), was applied the treatment differences were no longerstatistically significant. Clinical studies with Pimagedine, anotheragent inhibiting AGE formation, indicate that urinary albumin excretionwas not substantially reduced until at approximately one year afterinitiation of treatment with this inhibitor of AGE formation. Thus, atemporal dissociation exists between changes in serum creatinine andurinary albumin excretion with treatment using AGE inhibitors. Thistemporal dissociation explains the inability to see a significantreduction in albumin excretion during the 6 month PYR-206 study. Mostimportantly, the changes in serum creatinine, which is considered avalidated marker of renal function, are meaningful and consistent withthe observations in the higher dose study PYR-205/207.

A summary of data in the 206 study is shown in FIG. 1. FIG. 2 providesbaseline demographics for the study patient population. FIGS. 3 and 4summarize adverse event data, while FIG. 5 demonstrates that treatmentwith PYR also significantly reduced the incidence of sensory systemneurologic adverse events.

FIG. 6 provides a summary of tests that exceeded predesignated acut-off.

FIG. 7 provides a comparison of the results of the pyridoxamine clinicaltrial to previous clinical trials evaluating ACE-I and ARBs.

In addition, the urinary levels of TGF beta in the subjects completingthe PYR206 study (combined type 1 and type 2 patients) were tested. Thisgrowth factor is an important and accepted marker of renal disease,since it initiates or controls a cascade of cellular changes (fromdiabetes and other diseases) that lead to mesangial expansion andeventually fibrosis in the kidney. An analysis of the data indicatesthat while the levels of TGF beta (normalized to urinary creatininevalues and thus expressed as a ratio of pg TGF/mg Cr) increased 43% inthe placebo subjects during the six month duration of the study, thecorresponding values decreased about 24% in the PYR treated group (datanot shown). This is strong evidence of the action of PYR in retarding orhalting the nephropathy due to the diabetes.

In a separate study (“205/207 study”), diabetic nephropathy patientsreceived six months of treatment of escalating doses of pyridoxaminedihydrochloride (50 mg, 100 mg, and 250 mg), administered orally viacapsules twice daily as follows:

-   -   50 mg bid for 2 weeks, then if tolerated:    -   100 mg bid for 2 weeks, then if tolerated:    -   250 mg bid for 20 weeks.

The study drug was administered in addition to standard of care therapy.The patient population consisted of male and female patients between 18and 70 years of age with diabetic nephropathy associated with type 1 ortype 2 diabetes, serum creatinine of ≧3.5 mg/dL, and macroalbuminuriaconfirmed with baseline urinary albumin excretion ≧300 mg/24 hrs.

84 patients received at least one dose of the study drug (57 PYR; 27placebo).

Baseline characteristics of the patients included serum creatinine of1.75 mg/dL and urinary albumin excretion of 957 mg/12 h in treatment,versus 1.91 mg/dL and 1225 mg/12 h in placebo groups (FIG. 7 b).

No significant differences in treatment-related adverse events (35.1%PYR, 44.4% placebo) or study discontinuation due to AE's (8.8% PYR, 7.4%placebo) were observed. There was a higher rate of serious adverseevents in patients receiving pyridoxamine 21.1% PYR, 3.7% placebo. Basedon a review of similar studies, this imbalance is beleived to be theresult of an unexpectedly low rate of serious adverse events in theplacebo group. None of the treatment-related serious adverse events wereconsidered by independent medical reviewers to be related topyridoxamine dihydrochloride treatment.

In this higher dose study with pre-specified populations for statisticalanalyses, benefits of the study drug on various surrogate markers ofdiabetic renal disease were similar to those disclosed above for thefirst study (PYR-206). The mean rate of rise in serum creatinine was0.745 mg/dL/yr in placebo and 0.094 mg/dL/yr in PYR groups (p=0.0618 byProcMix repeated measure analysis). In addition, in type 2 diabeticpatients with a baseline serum creatinine of ≧1.3 mg/dL, the mean rateof rise in serum creatinine was 1.094 and 0.074 (p=0.0481 by ProxMixrepeated measure analysis) in placebo and PYR groups, respectively. In athird population of type 2 diabetic patients taking either an ACE-I orARB with a baseline serum creatinine ≧1.3 mg/dL, the rate of rise inserum creatinine was 0.035 mg/dL/yr in the PYR group and 1.414 mg/dL/yrin the placebo group (p=0.0106, by ProcMix repeated measure analysis)(See Table 9). Urinary TGF-β1 levels increased by 55.7% in the placebogroup while mean levels decreased by 13.1% in the PYR group. Due to thesmall number of adverse events in the sensory system, the same analysisas reported in PYR-206 would not have yielded meaningful results.

A summary of data in the 205/207 study is shown in FIG. 8. FIG. 9provides a comparison of the results of the pyridoxamine clinical trialto previous clinical trials evaluating ACE-I and ARBs.

1. A pharmaceutical composition comprising: (a) a dosage unit of 50 mgto 500 mg of pyridoxamine, or a pharmaceutically acceptable saltthereof; and (b) a pharmaceutically acceptable carrier.
 2. Apharmaceutical composition comprising: (a) pyridoxamine, or apharmaceutically acceptable salt thereof; and (b) one or more compoundsselected from the group consisting of angiotensin converting enzymeinhibitors, angiotensin receptor blockers, beta-blockers, aldosereductase inhibitors, calcium blockers, diuretics, glycosaminoglycans,insulin, incretin mimetics, insulin sensitizers, statins, fibrates,glucose uptake inhibitors, sulfonylureas, superoxide dismutase (SOD) andSOD mimetics, thiamine pyrophosphate and prodrugs thereof, transketolaseinhibitors, AGE inhibitors, and protein kinase C inhibitors.
 3. Thepharmaceutical composition of claim 2 wherein the one or more compoundsare selected from the group consisting of angiotensin converting enzymeinhibitors and angiotensin receptor blockers, or pharmaceuticallyacceptable salts thereof in a pharmaceutically acceptable carrier. 4.The pharmaceutical composition of claim 2, wherein the one or moretherapeutics comprises an angiotensin converting enzyme inhibitor. 5.The pharmaceutical composition of claim 4?, wherein the one or moretherapeutics comprises an angiotensin receptor blocker.
 6. A method forlimiting the progression of renal disease and/or diabetic complicationsin a human diabetic patient being treated with one or more therapeuticsselected from the group consisting of antihypertensive medications andglycemic control agents, comprising administering to the human diabeticpatient an amount of pyridoxamine, or a pharmaceutically acceptable saltthereof, effective to limit the progression of renal disease and/ordiabetic complications in the diabetic human patient.
 7. The method ofclaim 6 wherein the human diabetic patient is being treated with one ormore angiotensin converting enzyme inhibitors.
 8. The method of claim 6wherein the human diabetic patient is being treated with one or moreangiotensin receptor blockers.
 9. The method of claim 7 wherein thehuman diabetic patient has failed to respond adequately to angiotensinconverting enzyme inhibitor therapy.
 10. The method of claim 8 whereinthe human diabetic patient has failed to respond adequately toangiotensin receptor blocker therapy.
 11. The method of claim 6 whereinthe human diabetic patient has a baseline serum creatinine concentrationof greater than or equal to 1.3 mg/dL.
 12. The method of claim 6 whereinthe human diabetic patient has a whole blood HbA1C level of greater than6.5%.
 13. The method of claim 6 wherein the patient has elevated bloodlipid levels.
 14. The method of claim 6 wherein the human diabeticpatient has type II diabetes.
 15. The method of claim 11 wherein thehuman diabetic patient has type II diabetes
 16. A method for limitingthe progression of renal disease and/or diabetic complications in ahuman diabetic patient comprising administering to a human diabeticpatient with a baseline serum creatinine concentration of greater thanor equal to 1.3 mg/dL an amount of pyridoxamine, or a pharmaceuticallyacceptable salt thereof, effective to limit the progression of renaldisease and/or diabetic complications in the human diabetic patient. 17.A method for limiting the progression of renal disease and/or diabeticcomplications in a human diabetic patient, comprising administering to ahuman diabetic patient with a whole blood HbA1C level of greater than6.5% an amount of pyridoxamine, or a pharmaceutically acceptable saltthereof, effective to limit the progression of renal disease and/ordiabetic complications in the human diabetic patient.